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• Cheapest way to to determine if a MySQL connection is still alive

  - by MtnViewMark

  I have a pool of MySQL connections for a web-based data service. When it starts to service a request, it takes a connection from the pool to use. The problem is that if there has been a significant pause since that particular connection has been used, the server may have timed it out and closed its end. I'd like to be able to detect this in the pool management code. The trick is this: The environment in which I'm coding gives me only a very abstact API into the connection. I can basically only execute SQL statements. I don't have access to the actual socket or direct access to the MySQL client API. So, the question is: What is the cheapest MySQL statement I can execute on the connection to determine if it is working. For example SELECT 1; should work, but I'm wondering if there is something even cheaper? Perhaps something that doesn't even got across the wire, but is handled in the MySQL client lib and effectively answers the same question?

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• Does complex JOINs causes high coupling and maintenance problems ?

  - by ashkan.kh.nazary

  Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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• How to store some of the entity's values in another table using hibernate?

  - by nimcap

  Hi guys, is there a simple way to persist some of the fields in another class and table using hibernate. For example, I have a Person class with name, surname, email, address1, address2, city, country fields. I want my classes to be: public class Person { private String name; private String surname; private String email; private Address address; // .. } public class Address { private Person person; // to whom this belongs private String address1; private String address2; private String city; private Address country; // .. } and I want to store Address in another table. What is the best way to achieve this? Edit: I am using annotations. It does not have to be the way I described, I am looking for best practices. PS. If there is a way to make Address immutable (to use as a value object) that is even better, or maybe not because I thought everything from wrong perspective :)

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• Django sitemap intermittent www

  - by Jen Z

  The automatic sitemap for my Django site fluctuates between including the www on urls and leaving it out (I'm aiming to have it in all the time). This has ramifications in google not indexing my pages properly so I'm trying to narrow down what would be causing this issue. I have set PREPEND_WWW = True and my site record in the sites framework is set to include the www e.g. it's set to www.example.com as opposed to example.com. I'm using memcached but pages should expire from the cache after 48 hours so I wouldn't have thought that would be causing the issue? You can see the problem in effect at http://www.livingspaceltd.co.uk/sitemap.xml (refresh the page a few times). My sitemaps setup is fairly prosaic so I'm doubtful that that is the issue, but in case it's something obvious I'm missing here's the code: ***urls.py*** sitemaps = { 'subpages': Subpages_Sitemap, 'standalone_pages': Standalone_Sitemap, 'categories': Categories_Sitemap, } urlpatterns = patterns('', (r'^sitemap\.xml$', 'django.contrib.sitemaps.views.sitemap', {'sitemaps': sitemaps}), ... ***sitemaps.py*** # -*- coding: utf-8 -*- from django_ls.livingspace.models import Page, Category, Standalone_Page, Subpage from django.contrib.sitemaps import Sitemap class Subpages_Sitemap(Sitemap): changefreq = "monthly" priority = 0.4 def items(self): return Subpage.objects.filter(restricted_to__isnull=True) class Standalone_Sitemap(Sitemap): changefreq = "weekly" priority = 1 def items(self): return Standalone_Page.objects.all() class Categories_Sitemap(Sitemap): changefreq = "weekly" priority = 0.7 def items(self): return Category.objects.all()

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• parse xml with elementtree, custom sorting

  - by microspace

  I want to parse xml file in utf-8 and sort it by some field. Soring is made by custom alphabet (s1 from sourcecode). History of question is here: sorting of list containing utf-8 charachters. I've found how to sort xml here. Sorting work correctly, the problem is with elementtree, I must admit that it doesn't work on python3 Here is source code: #!/usr/bin/env python # -*- coding: utf-8 -*- #import xml.etree.ElementTree as ET # Python 2.5 import elementtree.ElementTree as ET s1='aáàAâÂbBcCçÇdDeéEfFgGgGhHiIîÎíiiIjJkKlLmMnNóoOöÖpPqQrRsSsStTuUûúÛüÜvVwWxXyYzZ' s2='11111122334455666aabbccddeeeeeeffgghhiijjkklllllmmnnooppqqrrsssssttuuvvwwxxyy' trans = str.maketrans(s1, s2) def unikey(seq): return seq[0].translate(trans) tree = ET.parse("tosort.xml") container = tree.find("entries") data = [] for elem in container: keyd = elem.findtext("k") data.append((keyd, elem)) print (data) data.sort(key=unikey) print (data) container[:] = [item[-1] for item in data] tree.write("sorted.xml", encoding="utf-8") Here are instructions to import elementtree module. When I import module this way :import xml.etree.ElementTree as ET, I get a message: Traceback (most recent call last): File "pcs.py", line 19, in <module> container[:] = [item[-1] for item in data] File "/usr/lib/python3.1/xml/etree/ElementTree.py", line 210, in __setitem__ assert iselement(element) AssertionError When I use this method to import: import elementtree.ElementTree as ET, I get this message: Traceback (most recent call last): File "pcs.py", line 4, in <module> import elementtree.ElementTree as ET File "/usr/local/lib/python3.1/dist-packages/elementtree/ElementTree.py", line 794, in <module> _escape = re.compile(eval(r'u"[&<>\"\u0080-\uffff]+"')) File "<string>", line 1 u"[&<>\"\u0080-\uffff]+" ^ SyntaxError: invalid syntax I use Python 3.1.3 (r313:86834, Nov 28 2010, 11:28:10). In python2.6 elementtree work without a problem. Content of tosort.xml: <xdxf> <entries> <ar><k>zaaaa</k>definition1</ar> <ar><k>saaaa</k>definition2</ar> ... ... </entries> </xdxf>

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• Long running operations (threads) in a web (asp.net) environment

  - by rrejc

  I have an asp.net (mvc) web site. As the part of the functions I will have to support some long running operations, for example: Initiated from user: User can upload (xml) file to the server. On the server I need to extract file, do some manipulation (insert into the db) etc... This can take from one minute to ten minutes (or even more - depends on file size). Of course I don't want to block the request when the import is running , but I want to redirect user to some progress page where he will have a chance to watch the status, errors or even cancel the import. This operation will not be frequently used, but it may happen that two users at the same time will try to import the data. It would be nice to run the imports in parallel. At the beginning I was thinking to create a new thread in the iis (controller action) and run the import in a new thread. But I am not sure if this is a good idea (to create working threads on a web server). Should I use windows services or any other approach? Initiated from system: - I will have to periodically update lucene index with the new data. - I will have to send mass emails (in the future). Should I implement this as a job in the site and run the job via Quartz.net or should I also create a windows service or something? What are the best practices when it comes to running site "jobs"? Thanks!

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• Writing good tests for Django applications

  - by Ludwik Trammer

  I've never written any tests in my life, but I'd like to start writing tests for my Django projects. I've read some articles about tests and decided to try to write some tests for an extremely simple Django app or a start. The app has two views (a list view, and a detail view) and a model with four fields: class News(models.Model): title = models.CharField(max_length=250) content = models.TextField() pub_date = models.DateTimeField(default=datetime.datetime.now) slug = models.SlugField(unique=True) I would like to show you my tests.py file and ask: Does it make sense? Am I even testing for the right things? Are there best practices I'm not following, and you could point me to? my tests.py (it contains 11 tests): # -*- coding: utf-8 -*- from django.test import TestCase from django.test.client import Client from django.core.urlresolvers import reverse import datetime from someproject.myapp.models import News class viewTest(TestCase): def setUp(self): self.test_title = u'Test title: bareksc' self.test_content = u'This is a content 156' self.test_slug = u'test-title-bareksc' self.test_pub_date = datetime.datetime.today() self.test_item = News.objects.create( title=self.test_title, content=self.test_content, slug=self.test_slug, pub_date=self.test_pub_date, ) client = Client() self.response_detail = client.get(self.test_item.get_absolute_url()) self.response_index = client.get(reverse('the-list-view')) def test_detail_status_code(self): """ HTTP status code for the detail view """ self.failUnlessEqual(self.response_detail.status_code, 200) def test_list_status_code(self): """ HTTP status code for the list view """ self.failUnlessEqual(self.response_index.status_code, 200) def test_list_numer_of_items(self): self.failUnlessEqual(len(self.response_index.context['object_list']), 1) def test_detail_title(self): self.failUnlessEqual(self.response_detail.context['object'].title, self.test_title) def test_list_title(self): self.failUnlessEqual(self.response_index.context['object_list'][0].title, self.test_title) def test_detail_content(self): self.failUnlessEqual(self.response_detail.context['object'].content, self.test_content) def test_list_content(self): self.failUnlessEqual(self.response_index.context['object_list'][0].content, self.test_content) def test_detail_slug(self): self.failUnlessEqual(self.response_detail.context['object'].slug, self.test_slug) def test_list_slug(self): self.failUnlessEqual(self.response_index.context['object_list'][0].slug, self.test_slug) def test_detail_template(self): self.assertContains(self.response_detail, self.test_title) self.assertContains(self.response_detail, self.test_content) def test_list_template(self): self.assertContains(self.response_index, self.test_title)

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• Django Database design -- Is this a good stragety for overriding defaults

  - by rh0dium

  Hi SO's I have a question on good database design practices and I would like to leverage you guys for pointers. The project started out simple. Hey we have a bunch of questions we want answered for every project (no problem) Which turned into... Hey we have so many questions can we group them into sections (yup we can do that) Which lead into.. Can we weight these questions and I don't really want some of these questions for my project (Yes but we are getting difficult) And then I'm thinking they will want to have each section have it's own weight.. Requirements So there's the requirements - For n number of project Allow a admin member the ability select the questions for a project Allow the admin member to re-weigh or use the default weights for the questions Allow the admin member to re-weight the sections Allow team members to answer the questions. So here is what I came up with. Please feel free to comment and provide better examples models.py from django.db import models from django.contrib.sites.models import Site from django.conf import settings class Section(models.Model): """ This describes the various sections for a checklist: """ name = models.CharField(max_length=64) description = models.TextField() class Question(models.Model): """ This simply provides a simple way to list out the questions. """ question = models.CharField(max_length=255) answer_type = models.CharField(max_length=16) description = models.TextField() section = models.ForeignKey(Section) class ProjectQuestion(models.Model): """ These are the questions relevant to the project """ question = models.ForeignKey(Question) answer = models.CharField(max_length=255) required = models.BooleanField(default=True) weight = models.FloatField(default = XXX) class Project(models.Model): """ Here is where we want to gather our questions """ questions = models.ManyToManyField(ProjectQuestion) Immediate questions: - When I start a project - any ideas on how to "pre-populate" the questions (and ultimately the weights) for the project? - Is there a generally accepted method for doing this process that I am missing? Basically the idea that you refer to the questions overide your own default weight, and store the answer? - It appears that a good chuck of the work will be done in the views and that a lot of checking will need to occur there? Is that OK? Again - feel free to give me better strategies!! Thanks

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• SQLite for personal use

  - by ALife

  What are the applications for your personal use that needs a small database like SQLite? I am thinking of trying a few popular databases and SQLite is surely the first one I am planning to try since I know barely nothing about database except some simple programming years ago. I learned that SQLite is good for personal use. But embarrassingly I do not see any application except maybe managing my list of phone numbers/contact info, which has probably a few hundred items. What's your experience? FYI, I use EndNote for my reference and softcopy of books, and I feel iTunes' music/media management is ok since I am not a frequent user anyway. And others? I do lots of coding, but I just use some simple etags tools for that. And I pretty much use .txt file (sometimes in the asciidoc style) for my notes. I have quite a bunch of notes, but not that many either. So, really, what are your personal applications that need a small database instead of existing tools and plain text files?

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• Pass Parameter to Subroutine in Codebehind

  - by Sanjubaba

  I'm trying to pass an ID of an activity (RefNum) to a Sub in my codebehind. I know I'm supposed to use parentheses when passing parameters to subroutines and methods, and I've tried a number of ways and keep receiving the following error: BC30203: Identifier expected. I'm hard-coding it on the front-end just to try to get it to pass [ OnDataBound="FillSectorCBList("""WK.002""")" ], but it's obviously wrong. :( Front-end: <asp:DetailsView ID="dvEditActivity" AutoGenerateRows="False" DataKeyNames="RefNum" OnDataBound="dvSectorID_DataBound" OnItemUpdated="dvEditActivity_ItemUpdated" DataSourceID="dsEditActivity" > <Fields> <asp:TemplateField> <ItemTemplate> <br /><span style="color:#0e85c1;font-weight:bold">Sector</span><br /><br /> <asp:CheckBoxList ID="cblistSector" runat="server" DataSourceID="dsGetSectorNames" DataTextField="SectorName" DataValueField="SectorID" OnDataBound="FillSectorCBList("""WK.002""")" ></asp:CheckBoxList> <%-- Datasource to populate cblistSector --%> <asp:SqlDataSource ID="dsGetSectorNames" runat="server" ConnectionString="<%$ ConnectionStrings:dbConn %>" ProviderName="<%$ ConnectionStrings:dbConn.ProviderName %>" SelectCommand="SELECT SectorID, SectorName from Sector ORDER BY SectorID"></asp:SqlDataSource> </ItemTemplate> </asp:TemplateField> </Fields> </asp:DetailsView> Code-behind: Sub FillSectorCBList(ByVal RefNum As String, ByVal sender As Object, ByVal e As System.EventArgs) Dim SectorIDs As New ListItem Dim myConnection As String = ConfigurationManager.ConnectionStrings("dbConn").ConnectionString() Dim objConn As New SqlConnection(myConnection) Dim strSQL As String = "SELECT DISTINCT A.RefNum, AS1.SectorID, S.SectorName FROM Activity A LEFT OUTER JOIN Activity_Sector AS1 ON AS1.RefNum = A.RefNum LEFT OUTER JOIN Sector S ON AS1.SectorID = S.SectorID WHERE A.RefNum = @RefNum ORDER BY A.RefNum" Dim objCommand As New SqlCommand(strSQL, objConn) objCommand.Parameters.AddWithValue("RefNum", RefNum) Dim ad As New SqlDataAdapter(objCommand) Try [Code] Finally [Code] End Try objCommand.Connection.Close() objCommand.Dispose() objConn.Close() End Sub Any advice would be great. I'm not sure if I even have the right approach. Thank you!

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• Java XML Output - proper indenting for child items

  - by Dr1Ku

  Hello, I'd like to serialize some simple data model into xml, I've been using the standard java.org.w3c -related code (see below), the indentation is better than no "OutputKeys.INDENT", yet there is one little thing that remains - proper indentation for child elements. I know that this has been asked before on stackoverflow , yet that configuration did not work for me, this is the code I'm using : DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); Document doc = builder.newDocument(); doc = addItemsToDocument(doc); // The addItemsToDocument method adds childElements to the document. TransformerFactory transformerFactory = TransformerFactory.newInstance(); transformerFactory.setAttribute("indent-number", new Integer(4)); // switching to setAttribute("indent-number", 4); doesn't help Transformer transformer = transformerFactory.newTransformer(); transformer.setOutputProperty(OutputKeys.METHOD, "xml"); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); DOMSource source = new DOMSource(doc); StreamResult result = new StreamResult(outFile); // outFile is a regular File outFile = new File("some/path/foo.xml"); transformer.transform(source, result); The output produced is : <?xml version="1.0" encoding="UTF-8" standalone="no"?> <stuffcontainer> <stuff description="something" duration="240" title="abc"> <otherstuff /> </stuff> </stuffcontainer> Whereas I would want it (for more clarity) like : <?xml version="1.0" encoding="UTF-8" standalone="no"?> <stuffcontainer> <stuff description="something" duration="240" title="abc"> <otherstuff /> </stuff> </stuffcontainer> I was just wondering if there is a way of doing this, make it properly indented for the child elements. Thank you in advance ! Happy Easter coding :-) !

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• How can I see which shared folders my program has access to?

  - by Kasper Hansen

  My program needs to read and write to folders on other machines that might be in another domain. So I used the System.Runtime.InteropServices to add shared folders. This worked fine when it was hard coded in the main menu of my windows service. But since then something went wrong and I don't know if it is a coding error or configuration error. What is the scope of a shared folder? If a thread in my program adds a shared folder, can the entire local machine see it? Is there a way to view what shared folders has been added? Or is there a way to see when a folder is added? [DllImport("NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode)] internal static extern System.UInt32 NetUseAdd(string UncServerName, int Level, ref USE_INFO_2 Buf, out uint ParmError); [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] internal struct USE_INFO_2 { internal LPWSTR ui2_local; internal LPWSTR ui2_remote; internal LPWSTR ui2_password; internal DWORD ui2_status; internal DWORD ui2_asg_type; internal DWORD ui2_refcount; internal DWORD ui2_usecount; internal LPWSTR ui2_username; internal LPWSTR ui2_domainname; } private void AddSharedFolder(string name, string domain, string username, string password) { if (name == null || domain == null || username == null || password == null) return; USE_INFO_2 useInfo = new USE_INFO_2(); useInfo.ui2_remote = name; useInfo.ui2_password = password; useInfo.ui2_asg_type = 0; //disk drive useInfo.ui2_usecount = 1; useInfo.ui2_username = username; useInfo.ui2_domainname = domain; uint paramErrorIndex; uint returnCode = NetUseAdd(String.Empty, 2, ref useInfo, out paramErrorIndex); if (returnCode != 0) { throw new Win32Exception((int)returnCode); } }

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• Does anyone have documentation on SHGetSysColor?

  - by Paulo Santos

  I'm trying to find any reference for this function, but I haven't found anything. All I have is an obscure KB from Microsoft referencing that a programmer made boo-boo when coding a part of the Windows Mobile 6 where he should call SHGetSysColor but instead he called GetSysColor that gives a complete different color, for the same spec. From what I could gather the GetSysColor read a color value in the registry from HKEY_LOCAL_MACHINE\Software\Microsoft\Color\SHColor or HKEY_LOCAL_MACHINE\Software\Microsoft\Color\DefSHColor and returns the color according to the index. In that registry I have the following value for a standard Win Mobile 6.5 "DefSHColor"=hex:\ ff,00,00,00,00,00,00,00,dd,dd,dd,00,ff,ff,cc,00,ff,ff,ff,00,15,af,bc,00,15,\ af,bc,00,c9,e7,e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00,14,9c,a7,00,14,9c,\ a7,00,15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,c9,e7,e9,00,37,c7,d3,00,37,c7,d3,\ 00,ff,ff,ff,00,00,b7,c9,00,14,9c,a7,00,ff,ff,ff,00,15,af,bc,00,84,84,c3,00,\ 15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,ff,ff,ff,00,00,00,00,00,ff,ff,ff,00,00,\ 00,00,00,ff,ff,ff,00,2e,44,4f,00,00,14,3c,00,00,f0,ff,00,ff,ff,ff,00,c9,e7,\ e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00 And I realized that each four bytes represents a different color (RR,GG,BB,AA -- The AA I'm assuming here, as every color there has the AA byte as 00 which would mean that it's a solid color). What I can't get a fix on is what each index mean, as I have 41 different colors in there. Googling for SHGetSysColor in gives me only 7 matches, two of them are the KB from Microsoft (one in English, the other in French) one is from a Russian site (which I don't read), yet another two are from the freepascal.org and one from Koders.com that is describing the commctl.def file. I went to the commctl.h trying to see if I could find reference tom this function, and found absolutely nothing. No search on MSDN, either fro Google, Bing, or the default MSDN search gave me any result. So, does anyone know what indexes are we talking about here?

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• ASP.Net MVC 2 - How to set up a Cancel button with client side navigation

  - by arame3333

  Thanks to a previous question I found a useful link on multiple buttons. http://weblogs.asp.net/dfindley/archive/2009/05/31/asp-net-mvc-multiple-buttons-in-the-same-form.aspx What I want to do is have a cancel button on my page, similar to this; <button name="button" type="button" onclick="document.location.href=$('#cancelUrl').attr('href')">Cancel</button> <a id="cancelUrl" href="<%: Url.Action("Index", "Home") %>" style="display:none;"></a> However although this code works, I really want to go back to the previous page. For Web Forms I could use the javascript Back() or Go(-1) functions, but they relied on postbacks. I could of course hard code the previous page and controller as I have done above. However I am struggling to find links that explain to me how Url.Action works. Because if I do this, I also need to include an index parameter, and I am not clear how the syntax works for that. It seems odd the amount of coding to do this. Out of curiosity, I am also wondering how you TDD client side code like this.

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• Is this a good job description? What title would you give this position?

  - by Zack Peterson

  Department: Information Technology Reports To: Chief Information Officer Purpose: Company's ________________ is specifically engaged in the development of World Wide Web applications and distributed network applications. This person is concerned with all facets of the software development process and specializes in software product management. He or she contributes to projects in an application architect role and also performs individual programming tasks. Essential Duties & Responsibilities: This person is involved in all aspects of the software development process such as: Participation in software product definitions, including requirements analysis and specification Development and refinement of simulations or prototypes to confirm requirements Feasibility and cost-benefit analysis, including the choice of architecture and framework Application and database design Implementation (e.g. installation, configuration, customization, integration, data migration) Authoring of documentation needed by users and partners Testing, including defining/supporting acceptance testing and gathering feedback from pre-release testers Participation in software release and post-release activities, including support for product launch evangelism (e.g. developing demonstrations and/or samples) and subsequent product build/release cycles Maintenance Qualifications: Bachelor's degree in computer science or software engineering Several years of professional programming experience Proficiency in the general technology of the World Wide Web: Hypertext Transfer Protocol (HTTP) Hypertext Markup Language (HTML) JavaScript Cascading Style Sheets (CSS) Proficiency in the following principles, practices, and techniques: Accessibility Interoperability Usability Security (especially prevention of SQL injection and cross-site scripting (XSS) attacks) Object-oriented programming (e.g. encapsulation, inheritance, modularity, polymorphism, etc.) Relational database design (e.g. normalization, orthogonality) Search engine optimization (SEO) Asynchronous JavaScript and XML (AJAX) Proficiency in the following specific technologies utilized by Company: C# or Visual Basic .NET ADO.NET (including ADO.NET Entity Framework) ASP.NET (including ASP.NET MVC Framework) Windows Presentation Foundation (WPF) Language Integrated Query (LINQ) Extensible Application Markup Language (XAML) jQuery Transact-SQL (T-SQL) Microsoft Visual Studio Microsoft Internet Information Services (IIS) Microsoft SQL Server Adobe Photoshop

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• Monotouch threads, GC, WCF

  - by cvista

  Hi This is a question about best practices i guess but it applies directly to my current MT project. I'm using WCF services to communicate with the server. To do this i do the following: services.MethodToCall(params); and the asynch: services.OnMethodToCallCompleted += delegate{ //do stuff and ting }; This can lead to issues if you're not careful in that variables defined within the scope of the asynch callback can sometimes be cleaned up by the gc and this can cause crashes. So - I am making it a practice to declare these outside of the scope of the callback unless I am 100% sure they are not needed. Now - when doing stuff and ting implies changing the ui - i wrap it all in an InvokeOnMainThread call. I guess wrapping everything in this would slow the main thread down and rubbish the point of having multi threads. Even though I'm being careful about all this i am still getting crashes and I have no idea why! I am certain it has something to do with threads, scope and all that. Now - the only thing I can think of outside of updating the UI that may need to happen inside of InvokeOnMainThread is that I have a singleton 'Database' class. This is based on the version 5 code from this thread http://www.yoda.arachsys.com/csharp/singleton.html So now if the service method returns data that needs to be added/updated to the Database class -I also wrap this inside an InvokeOnMainThread call. Still getting random crashes. So... My question is this: I am new to thick client dev - I'm coming from a web dev perspective where we don't need to worry about threads so much :) Aside from what I have mentioned -are there any other things I should be aware of? Is the above stuff correct? Or am i miss-understanding something? Cheers w://

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• Use of Syntactic Sugar / Built in Functionality

  - by Kyle Rozendo

  I was busy looking deeper into things like multi-threading and deadlocking etc. The book is aimed at both pseudo-code and C code and I was busy looking at implementations for things such as Mutex locks and Monitors. This brought to mind the following; in C# and in fact .NET we have a lot of syntactic sugar for doing things. For instance (.NET 3.5): lock(obj) { body } Is identical to: var temp = obj; Monitor.Enter(temp); try { body } finally { Monitor.Exit(temp); } There are other examples of course, such as the using() {} construct etc. My question is when is it more applicable to "go it alone" and literally code things oneself than to use the "syntactic sugar" in the language? Should one ever use their own ways rather than those of people who are more experienced in the language you're coding in? I recall having to not use a Process object in a using block to help with some multi-threaded issues and infinite looping before. I still feel dirty for not having the using construct in there. Thanks, Kyle

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• Understanding MongoDB(and NoSQL in general) and How to make the best use of it

  - by Earlz

  Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have 3 collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is what if the author's name changed. You'd have to go through updating a ton of posts and comments. But is this an ok thing to do with NoSQL?

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• Python/Sqlite program, write as browser app or desktop app?

  - by ChrisC

  I am in the planning stages of rewriting an Access db I wrote several years ago in a full fledged program. I have very slight experience coding, but not enough to call myself a programmer by far. I'll definitely be learning as I go, so I'd like to keep everything as simple as possible. I've decided on Python and SQLite for my program, but I need help on my next decision. Here is my situation 1) It'll be a desktop program, run locally on each machine, all Windows 2) I would really like a nice looking GUI with colors, nice screens, menus, lists, etc, 3) I'm thinking about using a browser interface because (a) from what I've read, browser apps can look really great, and (b) I understand there are lots of free tools to assist in setting up the GUI/GUI code with drag and drop tools, so that helps my "keep it simple" goal. 4) I want the program to be totally portable so it runs completely from one single folder on a user's PC, with no installation(s) needed for it to run (If I did it as a browser app, isn't there the possibility that a user's browser settings could affect or break the app. How likely is this?) For my situation, should I make it a desktop app or browser app?

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• Adding and removing elements efficiently from Collection object

  - by user569125

  Hi, Below coding is the working sample,but still i am not happy with this code with related to performancewise.Please have a look and let me know if any better approach is there.Thanks in advance. Adding items to the arraylist object String resultItems[] = paging.getMoveLeftArray().split(","); String fields[]={"id","name","name1"}; leftObj=new ArrayList(); for(int i=0;i<resultItems.length;i++){ //below line mea TestVO bean=new TestVO(); String resultItem = resultItems[i]; String idANDname[] = resultItem.split("@"); String id = idANDname[0]; // name or id should not contain "-" String name[] = idANDname[1].split("-"); //values and fileds are always having same length for(int j=0;j<name.length;j++) { PropertyUtils.setProperty(bean, fields[j], name[j]); } leftObj.add(bean); } Removing items from the arraylist object:availableList contains all the TestVO objects: String []removeArray=paging.getMoveRightArray().split(","); tempList=new CopyOnWriteArrayList(); newTempList=new CopyOnWriteArrayList(); for(int i=0;i<availableList.size();i++){ boolean flag = false; TestVO tempObj = (TestVO )availableList.get(i); int id =(Integer)tempObj.getId(); // System.out.println("id value"+id); // availableList.get(i).getClass().getField(name); for(int j=0;j<removeArray.length;j++){ String resultItem = removeArray[j]; String idandname[] = resultItem.split("@"); for(int k=0;k<idandname.length;k++){ String ids[]=idandname[0].split("-"); if(id==Integer.parseInt(ids[0])){ flag = true; break; } } } if(flag){ tempList.add(tempObj); } else{ newTempList.add(tempObj); }

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• Server side form validation and POST data

  - by tomcritchlow

  Hi, I have a user input form here: http://www.7bks.com/create (Google login required) When you first create a list you are asked to create a public username. Unfortuantely currently there is no constraint to make this unique. I'm working on the code to enforce unique usernames at the moment and would like to know the best way to do it. Tech details: appengine, python, webapp framework What I'm planning is something like this: first the /create form posts the data to /inputlist/ (this is the same as currently happens) /inputlist/ queries the datastore for the given username. If it already exists then redirect back to /create display the /create page with all the info previously but with an additional error message of "this username is already taken" My question is: Is this the best way of handling server side validation? What's the best way of storing the list details while I verify and modify the username? As I see it I have 3 options to store the list details but I'm not sure which is "best": Store the list details in the session cookie (I am using GAEsessions for cookies) Define a separate POST class for /create and post the list data back from /inputlist/ to the /create page (currently /create only has a GET class) Store the list in the datastore, even though the username is non-unique. Thank you very much for your help :) I'm pretty new to python and coding in general so if I've missed something obvious my apologies. Tom PS - I'm sure I can eventually figure it out but I can't find any documentation on POSTing data using the webapp appengine framework which I'd need in order to do solution 2 above :s maybe you could point me in the right direction for that too? Thanks! PPS - It's a little out of date now but you can see roughly how the /create and /inputlist/ code works at the moment here: 7bks.com Gist

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• How can I properly handle 404s in ASP.NET MVC?

  - by Brian

  I am just getting started on ASP.NET MVC so bear with me. I've searched around this site and various others and have seen a few implementations of this. EDIT: I forgot to mention I am using RC2 Using URL Routing: routes.MapRoute( "Error", "{*url}", new { controller = "Errors", action = "NotFound" } //404s ); The above seems to take care of requests like this (assuming default route tables setup by initial MVC project): "/blah/blah/blah/blah" Overriding HandleUnknownAction() in the controller itself: //404s - handle here (bad action requested protected override void HandleUnknownAction(string actionName) { ViewData["actionName"] = actionName; View("NotFound").ExecuteResult(this.ControllerContext); } However the previous strategies do not handle a request to a Bad/Unknown controller. For example, I do not have a "/IDoNotExist", if I request this I get the generic 404 page from the web server and not my 404 if I use routing + override. So finally, my question is: Is there any way to catch this type of request using a route or something else in the MVC framework itself? OR should I just default to using Web.Config customErrors as my 404 handler and forget all this? I assume if I go with customErrors I'll have to store the generic 404 page outside of /Views due to the Web.Config restrictions on direct access. Anyway any best practices or guidance is appreciated.

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• Returning a variable in a public void...

  - by James Rattray

  Hello, I'm abit new to programming Android App's, however I have come across a problem, I can't find a way to make global variables -unlike other coding like php or VB.NET, are global variables possible? If not can someone find a way (and if possible implement the way into the code I will provide below) to get a value from the variable 'songtoplay' so I can use in another Public Void... Here is the code: final Spinner hubSpinner = (Spinner) findViewById(R.id.myspinner); ArrayAdapter adapter = ArrayAdapter.createFromResource( this, R.array.colours, android.R.layout.simple_spinner_item); adapter .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); hubSpinner.setAdapter(adapter); // hubSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { //code Object ttestt = hubSpinner.getSelectedItem(); final String test2 = ttestt.toString(); Toast message1 = Toast.makeText(Textbox.this, test2, Toast.LENGTH_LONG); message1.show(); String songtoplay = test2; // Need songtoplay to be available in another 'Public Void' } public void onNothingSelected(AdapterView<?> parentView) { //Code } }); Basically, it gets the value from the Spinner 'hubSpinner' and displays it in a Toast. I then want it to return a value for string variable 'songtoplay' -or find a way to make it global or useable in another Public Void, (Which is will a button, -loading the song to be played) Please help me, Thanks alot. James

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• steps to fix a project that won't compile

  - by eco_bach

  Hi Pulling my hair out in trying to get a simple window based project to compile. I am running both 3.2.2 and 3.2.3 versions of Xcode. The latter is set up in a separate folder. Originally I used the latter to create and compile my project against the new 4.0 sdk. It compiled fine. Then I made the mistake of deleting some sdks I thought I no longer needed. Ever since I can no longer compile. Right now I get a dozen or so errors similar to the following "_OBJC_CLASS_$_CATransition", referenced from: objc-class-ref-to-CATransition in ViewTransitionsAppDelegate.o My active executable is the iphone simulator 4 and Base SDK is iPhone device 3.0. I tried reinstalling the xcode3.2.3 installer, no difference. I'm totally stymied, as my project WAS working and compiling fine, both to the simulator and external device. Are there any best practices or recommended steps in fixing or rebuilding a project when it won't compile? Any help welcome!

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• Batch Image compression tool for optimizing thousands of images

  - by Daniel Magliola

  Hi all, I'm maintaining a site that has thousands of images that have not been compressed nearly enough. The homepage weighs in at 1.5 Mb currently, and it could easily be way less that half that. I'm looking for some kind of tool that'll take a folder full of JPG pictures and will recompress them to their "optimal" compression value. Obviously, "optimal lossy compression setting" is an oxymoron, but I'm thinking maybe a tool that'll try different levels and compare the outputs to the input, and choose a "sweet spot" between size and destruction? Or even try whether PNG is a better option, many times it is, for "drawing" type stuff. Does anyone of you know any such tool? I'd have lots of fun coding one, but I bet someone already did and will save me 2 days. Alternatively, of course, anything that'll take all pictures in a folder and recompress them with a fixed quality level (say, 40) will also work, it'll just not make my inner nerd as happy, but it'll solve my problem just fine. (Ideally something that can run on Windows, ideally from the command line) Thank you!

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